sn

samson

07/08/2007 10:55 PM

Bending Wood Question

Hey Friends,

I am bending 1/8th strips of shag bark hickory to make
Native American ball sticks. For some reason, the wood
I harvested is cracking during the bend unlike any other
hickory I've used in the past.

Questions for you pro wood benders:

1) I harvested the wood a little late in the year (May).
Would this really make that much difference in bending?

2) Can the place where I harvested hickory make a big
difference? I got the wood 75 miles north of me in a state
park (with permission).

3) I've been trying to steam bend the wood. I built a steam
box using 4" PVC and a steam kettle. It seems to work ok. Using
the 1 inch per hour formula, I tried steaming for 10 minutes,
no luck. 20 minutes, no luck. 30 minutes, some luck. At what
point am I oversteaming the 1/8th inch strips to make them weak?
Should I go ahead steam even longer to make hopefully more
successful bends?

Thanks much for any help.

S.


This topic has 11 replies

Bb

BillinDetroit

in reply to samson on 07/08/2007 10:55 PM

09/08/2007 11:43 PM

Phisherman wrote:
You can remove the wood from the form after it cools. Expect
> 8% springback.
>

I am -simply- curious about this. Where did you get this figure and how
do you calculate for it in making a jig? I have a design in mind that
will call for a curve terminating in a 90 deg. turn as below:


=========<|||


and I am in the head-scratching phase of the jig design, having never
bent wood (at all) before.


Bill
--
I'm not not at the above address.
http://nmwoodworks.com


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Bb

BillinDetroit

in reply to samson on 07/08/2007 10:55 PM

12/08/2007 9:37 PM

ROY! wrote:

> Bill, I'm jumping in here a little late. Are you doing laminates
> bendups from thinly cut strips? If so, I can post a few pics of forms
> I've made for laminated table skirts and laminated rocking chair
> rocker.
>
> ROY!
>
>

Yes. It will look like 1/2 of a traditional heart shape with a flat to
hold a candle / oil lamp. The two halves are to interlink. Just any old
wood on the inside plies, something snazzy on the two exterior plies.

Bill


--
I'm not not at the above address.
http://nmwoodworks.com


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TT

"Toller"

in reply to samson on 07/08/2007 10:55 PM

08/08/2007 4:26 AM


> I am bending 1/8th strips of shag bark hickory to make
> Native American ball sticks. For some reason, the wood
> I harvested is cracking during the bend unlike any other
> hickory I've used in the past.
>

> 3) I've been trying to steam bend the wood. I built a steam
> box using 4" PVC and a steam kettle. It seems to work ok. Using
> the 1 inch per hour formula, I tried steaming for 10 minutes,
> no luck. 20 minutes, no luck. 30 minutes, some luck. At what
> point am I oversteaming the 1/8th inch strips to make them weak?
> Should I go ahead steam even longer to make hopefully more
> successful bends?
>
Never bent hickory, but I made some laminated chair rails with 1/8" oak; it
bent just fine without steaming.
Didn't the Native Americans use oak?

Yes, the 1/16" bent easier, but the 1/8" worked.

Pn

Phisherman

in reply to samson on 07/08/2007 10:55 PM

08/08/2007 11:17 AM

On Tue, 7 Aug 2007 22:55:14 -0500, samson <[email protected]> wrote:

>Hey Friends,
>
>I am bending 1/8th strips of shag bark hickory to make
>Native American ball sticks. For some reason, the wood
>I harvested is cracking during the bend unlike any other
>hickory I've used in the past.
>
>Questions for you pro wood benders:
>
>1) I harvested the wood a little late in the year (May).
>Would this really make that much difference in bending?
no

>
>2) Can the place where I harvested hickory make a big
>difference? I got the wood 75 miles north of me in a state
>park (with permission).
no

>
>3) I've been trying to steam bend the wood. I built a steam
>box using 4" PVC and a steam kettle. It seems to work ok. Using
>the 1 inch per hour formula, I tried steaming for 10 minutes,
>no luck. 20 minutes, no luck. 30 minutes, some luck. At what
>point am I oversteaming the 1/8th inch strips to make them weak?
>Should I go ahead steam even longer to make hopefully more
>successful bends?
15 to 20 minutes is about right, probably 20 minutes is better. You
need a full uninterrupted steam source during that time. Work
quickly--You have (only!) 20 seconds to bend the wood and get it into
the form after removing it from the steam box. Using thick leather
gloves, bend the wood gently. Steaming a piece twice doesn't work
well. You can remove the wood from the form after it cools. Expect
8% springback.

>
>Thanks much for any help.
>
>S.

Pn

Phisherman

in reply to samson on 07/08/2007 10:55 PM

12/08/2007 9:47 PM

On Thu, 9 Aug 2007 23:59:41 -0500, samson <[email protected]> wrote:

>In article <[email protected]>, [email protected]
>says...
>> Phisherman wrote:
>> You can remove the wood from the form after it cools. Expect
>> > 8% springback.
>> >
>>
>> I am -simply- curious about this. Where did you get this figure and how
>> do you calculate for it in making a jig? I have a design in mind that
>> will call for a curve terminating in a 90 deg. turn as below:
>>
>>
>> =========<|||
>>
>>
>> and I am in the head-scratching phase of the jig design, having never
>> bent wood (at all) before.
>>
>>
>> Bill
>
>A followup:
>
>1) Question about oak. It's good for bending, yes, but hickory
>is (usually) quite elastic and dries hard as a rock. So it's good
>for ballsticks.
>
>2) I reconfigured my steam box using a teapot that is more or less
>airtight and used a hose clamp so I would lose much steam. (Yes, I
>have a drip/steam release hole.)
>
>3) I only allowed myself 20 seconds after heating for 20 minutes. The
>results were excellent. I broke 2 (on a knotty part -- of the four
>sections of the blank I could cut and bend, these sections were
>the least knotty) and made 2 very good bends on clean strips with
>little or no knotty parts.
>
>I really appreciate the input and advice.
>
>S.

You may have already realized steam bending is more of an art than a
science. Recently I bent three different kinds of 1/8" thick wood.
The walnut bent easier than oak (surprise!), and the oak bent easier
than another (unknown) pinkish-colored wood. I broke about 1 out of
10 pieces when bending, but I say it was more due to operator fault
than the steaming process. Selecting long grain wood without knots
will give better results.

sn

samson

in reply to samson on 07/08/2007 10:55 PM

09/08/2007 11:59 PM

In article <[email protected]>, [email protected]
says...
> Phisherman wrote:
> You can remove the wood from the form after it cools. Expect
> > 8% springback.
> >
>
> I am -simply- curious about this. Where did you get this figure and how
> do you calculate for it in making a jig? I have a design in mind that
> will call for a curve terminating in a 90 deg. turn as below:
>
>
> =========<|||
>
>
> and I am in the head-scratching phase of the jig design, having never
> bent wood (at all) before.
>
>
> Bill

A followup:

1) Question about oak. It's good for bending, yes, but hickory
is (usually) quite elastic and dries hard as a rock. So it's good
for ballsticks.

2) I reconfigured my steam box using a teapot that is more or less
airtight and used a hose clamp so I would lose much steam. (Yes, I
have a drip/steam release hole.)

3) I only allowed myself 20 seconds after heating for 20 minutes. The
results were excellent. I broke 2 (on a knotty part -- of the four
sections of the blank I could cut and bend, these sections were
the least knotty) and made 2 very good bends on clean strips with
little or no knotty parts.

I really appreciate the input and advice.

S.

gc

ghost

in reply to samson on 07/08/2007 10:55 PM

15/08/2007 11:11 PM

BillinDetroit
I learned alot by reading up about steam bending from this
publication. http://www.fpl.fs.fed.us/documnts/usda/tb1267.pdf
also try thhis link, http://www.woodweb.com/KnowledgeBase/KBBWGeneral.
Go to group alt.binaries.pictures.woodworking. I posted pics of two
curved shelf facings I bent. I'll add it was a challenge.
Francis



On Sun, 12 Aug 2007 21:55:05 GMT, Phisherman <[email protected]> wrote:

>On Thu, 09 Aug 2007 23:43:36 -0400, BillinDetroit
><[email protected]> wrote:
>
>>Phisherman wrote:
>>You can remove the wood from the form after it cools. Expect
>>> 8% springback.
>>>
>>
>>I am -simply- curious about this. Where did you get this figure and how
>>do you calculate for it in making a jig? I have a design in mind that
>>will call for a curve terminating in a 90 deg. turn as below:
>>
>>
>>=========<|||
>>
>>
>>and I am in the head-scratching phase of the jig design, having never
>>bent wood (at all) before.
>>
>>
>>Bill
>
>The 8% springback is a guideline. It may be 5%, so you should design
>your bending jig with the thought that it may require a slight angle
>adjustment. If the jig is at an 84-degree angle, your wood, after it
>has cooled in the jig, will springback to abut 90 degrees. Different
>thickness and wood type make a difference. There are all kinds of
>steam bending jig designs and you need one where you can easily and
>quickly put the steamed wood into it and clamped without any fuss.
>Steam burns hurt--use care and leather gloves.

BH

Brian Henderson

in reply to samson on 07/08/2007 10:55 PM

08/08/2007 6:34 PM

On Tue, 7 Aug 2007 22:55:14 -0500, samson <[email protected]> wrote:

>I am bending 1/8th strips of shag bark hickory to make
>Native American ball sticks. For some reason, the wood
>I harvested is cracking during the bend unlike any other
>hickory I've used in the past.

I'd try to go for thinner laminations, 1/8", depending on the kind of
curves you're going for, may be kind of thick. Try it with 1/16" and
see if it helps.

ss

spaco

in reply to samson on 07/08/2007 10:55 PM

08/08/2007 10:19 AM

This is not an expert response, so act accordingly!!!

I went through this process recently trying to bend some 28 inch long
5/8" diameter spindles for repair of a rocking chair. My observations:

The maple dowels I first bought for this project didn't ever want to bend!

If the PVC isn't sagging, you aren't getting enough steam/heat.

You need a LOT of WET steam!!!!

So, here's what I did:

Switched to white oak.

Sawed out some 3/4" X 1 inch samples to try before spnending a lot of
time on the lathe

I got out my heat gun.
I laid the parts to be bent on the laundry tub and dribbled the hottest
water I could get from the tap over the part while passing the heat gun
blast back and forth over the part. I did this for 3 or 4 minutes.
Then the parts bent easily. It also seemed that the extra wettness gave
me a couple of minutes of bend time.

It seemed that the wetness helped me a lot, even though I read that
it's the heat, not the steam that makes bending work. The literature
did say that heat without water dries the wood out too fast.

Pete Stanaitis
------------------------

samson wrote:

> Hey Friends,
>
> I am bending 1/8th strips of shag bark hickory to make
> Native American ball sticks. For some reason, the wood
> I harvested is cracking during the bend unlike any other
> hickory I've used in the past.
>
> Questions for you pro wood benders:
>
> 1) I harvested the wood a little late in the year (May).
> Would this really make that much difference in bending?
>
> 2) Can the place where I harvested hickory make a big
> difference? I got the wood 75 miles north of me in a state
> park (with permission).
>
> 3) I've been trying to steam bend the wood. I built a steam
> box using 4" PVC and a steam kettle. It seems to work ok. Using
> the 1 inch per hour formula, I tried steaming for 10 minutes,
> no luck. 20 minutes, no luck. 30 minutes, some luck. At what
> point am I oversteaming the 1/8th inch strips to make them weak?
> Should I go ahead steam even longer to make hopefully more
> successful bends?
>
> Thanks much for any help.
>
> S.

Pn

Phisherman

in reply to samson on 07/08/2007 10:55 PM

12/08/2007 9:55 PM

On Thu, 09 Aug 2007 23:43:36 -0400, BillinDetroit
<[email protected]> wrote:

>Phisherman wrote:
>You can remove the wood from the form after it cools. Expect
>> 8% springback.
>>
>
>I am -simply- curious about this. Where did you get this figure and how
>do you calculate for it in making a jig? I have a design in mind that
>will call for a curve terminating in a 90 deg. turn as below:
>
>
>=========<|||
>
>
>and I am in the head-scratching phase of the jig design, having never
>bent wood (at all) before.
>
>
>Bill

The 8% springback is a guideline. It may be 5%, so you should design
your bending jig with the thought that it may require a slight angle
adjustment. If the jig is at an 84-degree angle, your wood, after it
has cooled in the jig, will springback to abut 90 degrees. Different
thickness and wood type make a difference. There are all kinds of
steam bending jig designs and you need one where you can easily and
quickly put the steamed wood into it and clamped without any fuss.
Steam burns hurt--use care and leather gloves.

Ri

ROY!

in reply to samson on 07/08/2007 10:55 PM

10/08/2007 10:38 AM

On Thu, 09 Aug 2007 23:43:36 -0400, BillinDetroit
<[email protected]> wrote:

>
>and I am in the head-scratching phase of the jig design, having never
>bent wood (at all) before.
>
>
>Bill

Bill, I'm jumping in here a little late. Are you doing laminates
bendups from thinly cut strips? If so, I can post a few pics of forms
I've made for laminated table skirts and laminated rocking chair
rocker.

ROY!


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